Capillaries are thin vessels that have a lining (endothelial lining) that is only one cell thick. The cells are held in place by the basement membrane (outer layer of capillaries). Since the capillaries are so thin, they facilitates the exchange of gases, nutrients, hormones, wastes between cells and blood. Arteries, veins and lymphatic vessels end in capillaries. The capillaries connect with each other to form a network. The capillaries are designed in such a way that they allow the transport of substances into and out of the vessel. There are structural differences to prevent or allow exchange of substances depending on where the capillaries are found. Water and ions are exchanged through the spaces between the cells (intercellular clefts) that make up the lining. There are areas where this is prevented by tight junctions that form impermeable barrier between cells. Large molecules like albumen are exchanged with the help of transport vesicles. There are 3 main types of capillaries based on pore structure. 1. Continuous- They do not have pores but posses intercellular clefts and areas with tight junctions. 2. Fenestrated- These have numerous pores of different sizes. They have a gylcocalyx layer that covers the inside of the capillaries. The gylcocalyx layer peeks out of the pores and is called the diaphragm (the intercellular clefts don\'t have the glycocalyx coming out of them). The diaphragm allows small molecules and prevents large molecules to pass through. But not all fenestrated capillaries have a glycocalyx layer. 3. Sinusodial (Discontinuous)- These have many intercellular clefts and pores and their basement membrane is incomplete.This type is the largest of the capillaries and the most permeable. They are found in the liver, spleen, bone marrow. Solution Capillaries are thin vessels that have a lining (endothelial lining) that is only one cell thick. The cells are held in place by the basement membrane (outer layer of capillaries). Since the capillaries are so thin, they facilitates the exchange of gases, nutrients, hormones, wastes between cells and blood. Arteries, veins and lymphatic vessels end in capillaries. The capillaries connect with each other to form a network. The capillaries are designed in such a way that they allow the transport of substances into and out of the vessel. There are structural differences to prevent or allow exchange of substances depending on where the capillaries are found. Water and ions are exchanged through the spaces between the cells (intercellular clefts) that make up the lining. There are areas where this is prevented by tight junctions that form impermeable barrier between cells. Large molecules like albumen are exchanged with the help of transport vesicles. There are 3 main types of capillaries based on pore structure. 1. Continuous- They do not have pores but posses intercellular clefts and areas with tight junctions. 2. Fenestrated- These have numerous pores of different sizes. They have a.